Implement Pango RenderText for Linux.

ui/gfx/gtk_util.h

 // Copyright (c) 2011 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef UI_GFX_GTK_UTIL_H_
 #define UI_GFX_GTK_UTIL_H_
 #pragma once
 
 #include <glib-object.h>
+#include <pango/pango-layout.h>
 #include <stdint.h>
 
 #include <string>
 #include <vector>
 
+#include "base/i18n/rtl.h"
 #include "base/memory/scoped_ptr.h"
 #include "ui/base/ui_export.h"
 
 typedef struct _GdkPixbuf GdkPixbuf;
 typedef struct _GdkRegion GdkRegion;
 typedef struct _GdkCursor GdkCursor;
 
 typedef struct _PangoContext PangoContext;
 
 class CommandLine;
 class SkBitmap;
 
 namespace gfx {
 
+class Font;
 class Rect;
 
 // Call gtk_init() using the argc and argv from command_line.
 // gtk_init() wants an argc and argv that it can mutate; we provide those,
 // but leave the original CommandLine unaltered.
 UI_EXPORT void GtkInitFromCommandLine(const CommandLine& command_line);
 
 // Convert and copy a SkBitmap to a GdkPixbuf. NOTE: this uses BGRAToRGBA, so
 // it is an expensive operation.  The returned GdkPixbuf will have a refcount of
 // 1, and the caller is responsible for unrefing it when done.
 UI_EXPORT GdkPixbuf* GdkPixbufFromSkBitmap(const SkBitmap* bitmap);
 
 // Modify the given region by subtracting the given rectangles.
 UI_EXPORT void SubtractRectanglesFromRegion(GdkRegion* region,
                                             const std::vector<Rect>& cutouts);
 
+// Setup pango layout |layout|, including set layout text as |text|, font
+// description based on |font|, width as |width| in PANGO_SCALE for RTL lcoale,
+// and set up whether auto-detect directionality, alignment, ellipsis, word
+// wrapping, resolution etc.
+void SetupPangoLayout(PangoLayout* layout,

[msw, 2011/08/23 08:01:01]

Hmm, I didn't suspect that moving the declaration up here would require you to
move the definition from canvas_skia_linux.cc to gtk_util.cc. I think it's
generally bad to add functions to *_util files, can all this pango stuff live in
canvas_skia_linux.* or render_text_linux.*? I might be wrong here, please
confirm with oshima or someone else.

[xji, 2011/08/23 23:52:52]

Ah, I think I mis-interpreted your previous comments.
I thought you'd like move the definition into gtk_util.
I do not think it is a good idea either.

And it would be better to declare that in canvas_skia.h and still define that in
canvas_skia_linux.cc

+                      const string16& text,
+                      const gfx::Font& font,
+                      int width,
+                      base::i18n::TextDirection text_direction,
+                      int flags);
+
 // Creates and returns a PangoContext. The caller owns the context.
 PangoContext* GetPangoContext();
 
 // Returns the resolution (DPI) used by pango. A negative values means the
 // resolution hasn't been set.
 double GetPangoResolution();
 
 // Returns a static instance of a GdkCursor* object, sharable across the
 // process. Caller must gdk_cursor_ref() it if they want to assume ownership.
 UI_EXPORT GdkCursor* GetCursor(int type);
 
 // Change windows accelerator style to GTK style. (GTK uses _ for
 // accelerators.  Windows uses & with && as an escape for &.)
 UI_EXPORT std::string ConvertAcceleratorsFromWindowsStyle(
     const std::string& label);
 
 // Removes the "&" accelerators from a Windows label.
 UI_EXPORT std::string RemoveWindowsStyleAccelerators(const std::string& label);
 
 // Makes a copy of |pixels| with the ordering changed from BGRA to RGBA.
 // The caller is responsible for free()ing the data. If |stride| is 0, it's
 // assumed to be 4 * |width|.
 uint8_t* BGRAToRGBA(const uint8_t* pixels, int width, int height, int stride);
-

[msw, 2011/08/23 08:01:01]

replace this line. (I think the common/proper style includes it)

 }  // namespace gfx
 
 // It's not legal C++ to have a templatized typedefs, so we wrap it in a
 // struct.  When using this, you need to include ::Type.  E.g.,
 // ScopedGObject<GdkPixbufLoader>::Type loader(gdk_pixbuf_loader_new());
 template<class T>
 struct ScopedGObject {
   // A helper class that will g_object_unref |p| when it goes out of scope.
   // This never adds a ref, it only unrefs.
   template<class U>
   struct GObjectUnrefer {
     void operator()(U* ptr) const {
       if (ptr)
         g_object_unref(ptr);
     }
   };
 
   typedef scoped_ptr_malloc<T, GObjectUnrefer<T> > Type;
 };
 
 #endif  // UI_GFX_GTK_UTIL_H_